Keldagrim is the city of the dwarves. Its name derived from the River Kelda flowing through the city, and it is a massive underground dwarven city accessible from the tunnel entrance east of Rellekka. It is accessed through The Giant Dwarf quest. The entrance of Keldagrim is near Rellekka. This is also the home of the Blast Furnace.

Including the mines to the south and the Arzinian Mine within those mines, Keldagrim is one of the largest dungeons in all of RuneScape. The only other dungeons that rival its size are Varrock Sewers, Taverley Dungeon, the Underground Pass, Dorgesh-Kaan, Brimhaven Dungeon, and the God Wars Dungeon. Despite its size and large array of features, Keldagrim is rarely visited by the vast majority of players. The exception to this is on World 358, which has been declared the official Blast Furnace world. Although the city often lacks players, it has no shortage of non-player inhabitants - Keldagrim boasts one of the largest NPC populations of any city in the game.